A screen of a smartphone is usually a touch screen, and the touch screen may respond to a touch operation of a user.
A display state of the screen can be classified into an active state and an inactive state. When the screen is in the active state, the screen may respond to a touch operation. When the screen is in the inactive state, the screen responds only to a wake-up operation but not to other operations. In order to save energy consumption of a mobile phone and to avoid misoperation of the user, the screen is usually in the inactive state when the user does not use the mobile phone. When the user needs to use the mobile phone, he/she switches the screen from the inactive state to the active state through the wake-up operation.
Since the dimming or brightening of the screen of the smart phone is usually implemented according to triggering of a physical key or touch operation on the screen, the operation manner is poor, which cannot meet more requirement of operating the screen from the user.